1. Field of the Invention
The invention concerns a textile machine for the manufacture of textile products from threads with a thread processing device which has at least one thread control device movable in one direction by a form-fitting drive and in the opposite direction by a force-fitting pneumatic drive.
2. Description of the Prior Art
Numerous textile machines are known, for example in the form of weaving looms (U.S. Pat. No. US-PS! 3 603 351, U.S. Pat. No. US-PS! 3 695 304, Swiss Patent CH-PS! 531 588, Europatent EP-PS! 0 107 099, Europatent EP-PS! 0 325 547, published unexamined European patent application EP-OS! 0 363 311, published unexamined German patent application DE-OS! 31 20 097) or knitting loom (DE-A-27 58 421).
For shed formation, weaving machines comprise thread processing devices that move the warps from a middle shed position into a upper or lower position, in order to open a shed, into which a weft thread is introduced, which is then cast against an edge.sup.1 of the cloth by means of a weaving reed. For shed formation, the most varied devices are used, such as heddle frames and single heddle controls, for the driving of which crank mechanisms, cam plates, cam gears, dobbie looms, jacquard machines or similar being used. In this respect, one distinguishes, as a rule, between two types of drives; a positive drive, such as a crank mechanism, in which driving takes place in both directions of movement according to the form-fitting principle, i.e. in a positive manner, and a negative drive.
With a negative drive, for example cam plates, cam gears, dobbie looms, jacquard machines, and similar, driving takes place in one direction of movement according to the form-fitting principle, i.e. in a positive manner, and in the other direction of movement according to the force-fitting principle, i.e. in a negative manner, for example via extension springs, pressure springs, leaf springs, or torsion springs.
The disadvantage of a positive drive lies in the fact that, in particular with high numbers of revolutions, the mounting areas are punched out and become loose. On the one hand, this causes great noise development, and, on the other hand, inaccuracies, and finally failure of the drive. Such a drive is, for example, not suitable for more than 2,000 revolutions per minute.
With a negative drive, the category, to which the invention herein belongs, driving according to the force-fitting principle takes place by means of extension, pressure, leaf or torsion springs of leaf steel, rubber and synthetic elastomers. Because the force-fitting drive always acts against the form-fitting drive, problems result at higher numbers of revolutions. Thus, for example, in many systems co-vibrations occur that cause the drive parts to get out of control, i.e. the drive parts are no longer situated in a prestressed state with respect to each other. This causes great noise development, failure of the mounting areas, breaking of the springs and ultimately, as a result, complete failure of the thread control. Steel springs are moreover relatively long and heavy, causing a low resonance number of revolutions. With rubber and Elasthan springs, the problems lie in the molecular friction of the material, causing major temperature increases of the springs. Such major temperature increases cause premature aging and loss of the elastic characteristics which, in turn, causes a low resonance number of revolutions, inadequate elastic characteristics, and ultimately their failure. From this results ultimately a drastic reduction in the degree of utility, the efficiency and the production output of such textile machines. It has been found that thread processing devices for shed formation of a weaving loom using the following materials are subject to obvious limitations in the case of force-fitting drives with:
steel extension springs 1,500 rpm max. PA1 steel pressure springs 2,000 rpm max. PA1 rubber extension springs 3,000 rpm max. PA1 Elasthan springs 2,500 rpm max.
Moreover, as a rule, such thread processing machines have a relatively large design volume and, while running, cannot be adjusted to the operating conditions of the textile machine.
From German examined patent application DE-AS! 26 31 175, a weaving loom of the type mentioned in the introduction is known, in which the retraction for the heddles of a jacquard machine is pneumatically generated. In this design, in each case, the heddles are connected to a piston/cylinder group, the cylinders communicating with a joint large-volume gas chamber so that a retraction force, common to all the heddles and constant over the entire retraction path of the heddle, is available. Individual pneumatic control of every heddle is, therefore, impossible.